The invention relates to attractants for yellow jackets and their use in traps for yellow jackets. The attractants have improved overall effectiveness in attracting yellow jackets, in attracting a broader spectrum of yellow jacket species and in attracting yellow jackets in the several phases of their life cycles when their food requirements vary.
Yellow jackets are of the genus Vespa of which there are about 30 species in North America. Of these, the more common of the North American yellow jackets are Vespula vulgaris, Vespula rufa, Vespula germanica (mostly found in northeastern states); Vespula pensylvanica (mostly found in western states) and Vespula squamosa (mostly found in southern states.) These species are aggressive and may attack people without particular provocation. Note in passing that in Europe yellow jackets are usually referred to as xe2x80x9cEuropean wasps.xe2x80x9d
The life cycle of the yellow jacket begins in the early spring when an over-wintering mated queen is nested. The queen feeds on carbohydrates such as nectar and gathers high protein substances as larval food for the first brood of workers. After emergence of the workers, however, she remains in the nest. During late spring and summer, as subsequent broods of larvae are reared and established, increasing quantities of high protein materials are needed to support the yellow jacket colonies. In the summer new queens and males are produced in the colony and emerge to find mates as when exploring flowers for nectar. The new queens mate and almost immediately find a site in which to hibernate over the winter until the following year.
Yellow jackets are aggressive when searching for food and, on occasion, can make a small area almost uninhabitable for humans. This condition can exist, for example, at camp and picnic sites, restaurants, zoos or other locations where yellow jackets congregate to scavenge exposed food or garbage.
One method used to reduce the population of yellow jackets is to entice workers of the scavenging species to enter baited traps. The traps contain attractants (bait) which lure the yellow jackets into the traps. The literature sometimes refers to chemical attractants to distinguish them from food and nutritional attractants. Since the distinction between the two is not always clear, and since the distinction serves little purpose in understanding or practicing the herein described invention, the terms xe2x80x9cattractant(s)xe2x80x9d and xe2x80x9cbaitxe2x80x9d are used generically in the specification and the attached claims to include materials that arouse the interest of yellow jackets and lure them into traps. Traps making use of chemical attractants have the advantage of needing less attention than do those with food attractants since chemicals are less likely to spoil and rot than are conventional meat and fish attractants.
Traps are basically of two different types and functionality. One type of trap allows yellow jackets to enter easily enter but confuses them in finding their way out. Most of these types of traps make use of a screen rolled into a cone open at both its top and bottom, much like a megaphone. The workers may readily find their way into the traps through the large end of the cone but difficulty, in finding their way back out through the narrower opening. The same effect can be obtained by locating a series of small openings, often on the lid of the trap, that are just large enough to let yellow jackets enter the trap, but too small to let them find their way back out. Eventually the trapped yellow jackets die from lack of food and water. For convenience these traps are referred to as xe2x80x9cdryxe2x80x9d traps.
A second kind of trap may be referred to a xe2x80x9cwetxe2x80x9d trap. A wet trap has a liquid at the bottom of the trap to which an insecticide has been added or is a drowning fluid. The insecticides kill the yellow jackets in the trap. The drowning fluidxe2x80x94water to which a surfactant has been addedxe2x80x94xe2x80x9cwet outxe2x80x9d the wings and body of the insect so that it cannot fly and the insect drowns in the water. The attractants of the instant invention will perform well either as wet or dry traps.
Since yellow jackets feed upon two basic types of materials, adults primarily on carbohydrates and larvae on proteins, a combination of the two is usually most effective as bait. However, excessive use of carbohydrates should be avoided as many of the beneficial hymenopterous insects, such as the honey bee, are also attracted to carbohydrates.
Glue boards have been used to trap yellow jackets. Here a substrate is provided with a combination of an attractant and a sticky material with permanent tack. When a yellow jacket lands on the glue board it becomes mired in the sticky material and can""t fly away. Glue boards are a variation of the once popular fly paper.
One of the oldest ways of controlling yellow jacket populations involves suspending raw fish over a pan filled with water and a wetting agent. The skin of the fish is cut or broken to give the yellow jackets ready accesses to the flesh of the fish. Typically, a yellow jacket worker will cut a piece from the flesh of the fish and fly a short distance to trim the piece into a more manageable size. Frequently, however, the piece is too large for the yellow jacket to carry. If the yellow jacket refuses to release a large piece of fish, it falls into the pan of water and drowns. While these traps work well, they suffer from the disability of requiring frequent attention to rebate the traps with fresh fish and to replace the fish taken from the traps by carnivorous wildlife.
The instant invention does not depend upon a trap of any articular design. However, to illustrate the kind of traps in which the attractants for yellow jackets may used, reference is made, for example, to U.S. Pat. No. 3,803,753. Here there is disclosed a container, such as an ordinary can or jar, with a removable lid. As illustrated in the drawings of the patent, the lid has a number of holes about 0.5 inches in diameter at spaced intervals around the periphery. Yellow jackets can crawl through the holes but can""t find their way out.
The bait suggested for use in the ""753 patent is a fish-flavored proteinaceous food, such as cat food, flavoring and a small amount of a toxicant dissolved in the food.
U.S. Pat. No. 4,551,941 is an example of a configuration for a trap that is also useful in the practice of this invention. Here a transparent cylindrical insect trap is disclosed that provides a bottom entry to a circular truncated entry cone. The small end of the cone terminates within the cylindrical entrapment chamber. A screened orifice is provided to permit the escape of volatile olfactory attractants. The patent advises that colors may be used with advantage as optical attractants.
It is the principal object of the invention to provide attractants for yellow jackets that are more effective than those known in the prior art.
A related object of the invention is to provide an attractant for yellow jackets that is effective to attract more varieties of the common species of yellow jackets.
It is also an object of the invention to provide an attractant for yellow jackets that can be used effectively in diverse geographic regions.
Another object of the invention is to provide an attractant that can be used to good effect in either xe2x80x9cdryxe2x80x9d or xe2x80x9cwetxe2x80x9d traps.
Another object of the invention is to provide an attractant for yellow jackets that is safe, non-toxic and environmentally friendly.
Another object of the invention is to provide an attractant for use in traps for yellow jackets that has a long shelf life, is stable in use over prolonged periods of time and requires minimum attention or maintenance.
Yet another object of the invention is to provide an attractant that is effective over several phases in the life cycles of yellow jacket colonies, such as, for example, when either protein or carbohydrate foods are most in demand.
Still another object of the invention is to provide an effective attractant for yellow jackets that will not be harmful to hymenopterous insects.
These and other objects of the invention are achieved by the addition of a weak acid to known formulations for yellow jacket attractants. While the addition of a weak acid has proven beneficial in improving the effectiveness of many different formulations for yellow jacket attractants, mixtures of saccharides and proteins are the preferred attractants for use in the invention. In these preferred attractants apple juice concentrate may be utilized as the saccharide and powdered eggs or powdered poultry as the protein. A small amount of detergent added to water provides a convenient drowning solution.
The addition of a small amount of a weak acid to yellow jacket attractants has shown significant improvements in attracting a considerable range of yellow jacket species, in proving effective during the several phases of a yellow jackets life cycle and in not attracting beneficial hymenopterous insects. It is believed that no yellow jacket attractants are known that combine these desirable properties so effectively.
Dilute acetic acid is a useful weak acid for use in the practice of the invention and vinegar is a convenient and readily available source. It is noted that U.S. Food and Drug Administration proscribe that, unless otherwise modified, the term xe2x80x9cvinegarxe2x80x9d refers to a product derived from apples which contains at least 5 g. of acetic acid per 100 ml. of product. Other sources define a xe2x80x9cvinegarxe2x80x9d as a compound that contains about 5 g acetic acid without regard to its source. For example, the Concise and Technical Dictionary of the Chemical Publishing Company, Inc. dated 1947 defines xe2x80x9cvinegarxe2x80x9d as a xe2x80x9cSolution containing a minimum if 4% acetic acid, produced by the bacterial oxidation of alcoholic liquors.